Asymmetric total synthesis of sperabillins B and D via lithium amide conjugate addition
Stephen G. Davies,Jane R. Haggitt,Osamu Ichihara,Richard J. Kelly,Michael A. Leech,Anne J. Price Mortimer,Paul M. Roberts,Andrew D. Smith
Organic & Biomolecular Chemistry Pub Date : 08/24/2004 00:00:00 , DOI:10.1039/B404962D
Abstract

Diastereoselective conjugate addition of homochiral lithium (R)-N-allyl-N-α-methylbenzylamide to methyl (2E,5E)-hepatadienoate, followed by protecting group manipulation and subsequent iodocyclocarbamation allows a concise route to the core fragment, methyl (3R,5R,6R)-3,6-diamino-5-hydroxyheptanoate, of sperabillins B and D. Differentiation between the C-3 and C-6 primary amino groups of this core amino acid was readily achieved by treatment with acetone, giving the 5,6-isopropylidene and C-3-imine protected diamine, with subsequent regioselective acylation of the C-6-nitrogen facilitating the total synthesis of sperabillin D in 10.8% overall yield, and the first asymmetric synthesis of sperabillin B in 5.8% overall yield.

Graphical abstract: Asymmetric total synthesis of sperabillins B and D via lithium amide conjugate addition